The present invention relates to a frozen food and a process for manufacturing the same, particularly to a frozen food product obtained by mixing a major ingredient such as rice in pilaf or risotto, or pasta in pasta salad or macaroni au gratin with auxiliary ingredients including sauces and other ingredients (including chopped vegetables and the like) to be cooked with the major Ingredient and freezing the resulting mixture, as well as, a process for manufacturing the same.
In a general and conventional process for manufacturing a frozen rice, when rice is mixed with a sauce, the sauce is admixed beforehand together with other ingredients to the rice, and the resulting mixture is boiled, or after a rice is boiled, a sauce and other ingredients are admixed thereto. The resulting sauced rice is subjected to individual quick freezing using various types of freezing machines, so that grains of boiled rice are not integrated into blocks. There are known techniques for achieving individual quick freezing of rice, which include, for example, the drum tumbling method using a refrigerant such as liquefied nitrogen and dry ice and a fluid agitation method utilizing cold air generated by a freezing machine.
Meanwhile, in the field of frozen rice, there have been expected demands for foods having high water contents, for example, a wet type frozen rice having a water content of 65% or more, which forms a rice porridge containing additional ingredients or a risotto when unfrozen. However, in the conventional freezing techniques, a sauce having a high water content is admixed to rice prior to the freezing step, so that the water contained in the sauce migrates into the rice to impair texture of the rice and that the rice grains deposit to the interior of the freezing machine or the mixer, due to the adhesiveness of the sauce itself and to the effects of mixing and kneading in the temperature region before the freezing step. The deposit can grow gradually into massive clusters, which apply overload to the freezing machine and the like and prevent them from operating smoothly. This sometimes makes it impossible to carry out continuous production. Meanwhile, in order to obtain an individually frozen rice by admixing a sauce to a boiled rice and freezing the resulting mixture, the ratio of the sauce to be added should be less than 10 wt % in order to achieve individual quick freezing. As described above, the freezing step in the prior art has been a great hindrance in obtaining a wet type frozen rice in a desirable state.
Accordingly, wet type frozen rice products commercially available currently are not manufactured by means of individual quick freezing but are predominantly those manufactured by means of block freezing (block-frozen products). However, the block-frozen products involve a problem that they take much time for unfreezing, inconveniently.
Meanwhile, there are products of the type which are distributed in packages each containing a pack of rice and a packet of sauce, and consumers unfreeze them and mix them (frozen products with sauce packets). However, this type of products are not preferred, because they put much trouble to consumers, and manufacturers must prepare the same number of sauce packets as that of the products, imposing them a great burden for inventory control.
Further, there is another type of product obtained by preparing small blocks of frozen sauce (ca. 10 mm cubes) separately from a rice freezing step and admixing them to the individually frozen rice (frozen products with frozen sauce cubes admixed). However, a sauce having a high viscosity does not commingle with the rice homogeneously at the time of unfreezing to mar the taste of the product, so that not only the commercial value of the product is lowered but also production process requires extra steps, causing rise in the cost, disadvantageously. In addition, in the case where a necessary amount of product is taken out from a package and is cooked, the rice and the sauce cannot necessarily be taken out at a constant ratio, and variation is likely to occur in the amount of sauce in the cooked food.
The same applies to a pasta dish cooked by mixing a boiled and drained pasta such as elbow and penne with a tomato sauce or a cream sauce.
As described above, the conventional sauced frozen rice, wet type frozen rice and sauced frozen pasta are inconvenient in view of distribution and consumption, and there is no product of commercial value fitting consumers"" needs at present.
It is an object of the present invention to establish a process for manufacturing efficiently products by means of individual quick freezing, in which a major ingredient such as rice grains and pasta pieces are mixed homogeneously with a sauce. More specifically, the objective of the present invention is to provide an unconventional frozen food product of high added value, which enables consumers to unfreeze by such a simple and easy way as has been used for the conventional products prepared by individual quick freezing, and which gives a stable quality (the ratio of rice or pasta to sauce is constant) even when it is packaged portionwise to facilitate portion control and also to provide a process for manufacturing the same.
The frozen food product according to the present invention contains as a major ingredient boiled rice grains or boiled pasta pieces, a water migration-preventing layer formed on the surface of each rice grain or pasta piece, and a sauce layer formed on the surface of the water migration-preventing layer, and the product is frozen in such a state.
The thus formed frozen product has excellent texture, since the sauce is hardly molten by temperature rises, and even if the product once unfrozen is frozen again into a block, it can be returned easily to the original individually frozen state. The unfrozen or cooked rice grains or pasta pieces hardly absorb the water contained in the sauce.
The water migration-preventing layer is a sauce layer formed using a primary sauce of a composition different from that of a secondary sauce forming the external sauce layer. Here, the primary sauce preferably has a sugar content (Brix) of 10 to 40xc2x0. The secondary sauce preferably has a sugar content (Brix) of 0 to 25xc2x0. The water migration-preventing layer may be a starch layer, an oil film layer or a mixture of a starch and an oil.
Meanwhile, in the case of a pasta, pasta pieces may each be covered on the surface with a sauce layer having a small water content.
The process for manufacturing a frozen food product according to the present invention includes a primary sauce mixing step where a primary sauce is admixed to a major ingredient such as a rice boiled after washing and impregnation with water or a boiled and drained pasta; a first freezing step where the thus treated major ingredient is frozen; a secondary sauce mixing step where a secondary sauce having a composition different from that of the primary sauce is admixed to the thus frozen major ingredient; and a second freezing step where the resulting major ingredient is frozen.
In the above method, the primary sauce is admixed in an amount of 5 to 20% by weight based on the weight of the major ingredient. Meanwhile, when the major ingredient is a boiled rice, the secondary sauce is admixed in an amount of 10 to 40% by weight based on the weight of the boiled rice. When the major ingredient is a pasta, the secondary sauce is admixed preferably in an amount of 10 to 50% by weight based on the weight of the pasta. Further, when the major ingredient is a boiled rice, it is obtained by adding an oil or a fat to an impregnated rice, and boiling the resulting mixture. Here, the oil or fat is added suitably in an amount of 1 to 5% by weight based on the weight of the rice before the boiling treatment.
Meanwhile, when the major ingredient is a boiled rice, a starch is added to a washed rice or to water for impregnating it, and then the rice is impregnated with the resulting mixture. Here, the starch is admixed suitably in an amount of 0.1 to 10% by weight based on the weight of the rice before the boiling treatment.
According to the process of the present invention described above, a frozen rice or frozen pasta in which rice grains or pasta pieces are mixed homogeneously with a sauce can be manufactured efficiently by means of individual quick freezing. Meanwhile, consumers can unfreeze it by such a simple and easy way as has been used for the conventional rice or pasta products prepared by individual quick freezing. In addition, the frozen food product gives stable quality (where the ratio of rice or pasta to sauce is constant) even when it is packaged portionwise, to facilitate portion control. Thus, the present invention can give unconventional frozen food products of high added value.